High temperature cut-off switch and immersed rod assembly for hot water generating tanks



Feb. 2, 1 960 F. E. THELEN 2,923,797 HIGH TEMPERATURE CUT-OFF SWITCH ANDIMMERSED ROD ASSEMBLY FOR HOT WATER GENERATING TANKS Filed July 1, 1957VALVE. ME HANiM HIGH TEMPERATURE CUT-OFF SWITCH AND IM- MERSED RODASSEMBLY FOR HOT WATER GENERATING TANKS Floyd E. Thelen, Atchison,Kans., assignor to Luxra Company, Atchison, Kans., a corporation ofKansas Application July 1, 1957, Serial No. 669,229 3 Claims. (Cl.200-137) This invention relates to a high temperature cut-ofl for hotwater heaters and more particularly to electrical cutoffs therefor forattachment to magnesium rod fittings therefor, although it may beadvantageously employed in connection with other fittings on hot waterheaters.

tain the water temperature at safe maximum limits under all conditions.

Most every modern quality hot water heater is provided with a safetyshut-ofi to insure the safe operation thereof should the gas pilot failor the burner shut off or terminate the generation of hot water afterreaching a pre-set temperature limit. Then, too, quality instantaneoushot water heaters are now equipped with magnesium rods to minimize thecorrosion of the water tank and to add to the life thereof. This rodconducts the heat of the water very rapidly to the body of the tank, andparticularly to the body top end thereof to provide the most effectivetemperature indicator response area thereof.

In ':'order to provide the most efiective temperature control of hotwater generating tank heaters through the medium of a single openingtherein, an improved simple fitting has been provided to extend throughthe customary and standard threaded opening in the tank for mounting ofa temperature responsive switch at one end and a magnesium rod at theother end. This is effected with a double threaded pipe fitting havingan exteriorly threaded tank engaging portion and an internally threadedend to threadedly receive and connect an element thereto such as aninternally suspended magnesium rod in water immersed relation to a hotwater generating tank. The exterior surface of the fitting is providedwith a simple and eifective thermally responsive electric switch mountedthereon to quickly respond to temperature changes in the water to insureeflicient operation.

One object of the present invention is to provide a simple fittinghaving threaded portions for mounting of exteriorly and interiorlydisposed operating elements in relation to a hot water generating tank.

Another object is to provide a cylindrical fitting with intermediatethreads for mounting two operating elements in relation to a threadedtank opening serving as a support therefor.

Still another object is to provide a hot water generating tank with anexternally threaded fitting having a threaded portion for connectionthereto and another threaded inside end for mounting of elements inwater immersed relation with a tank for mounting of a thermallyresponsive electric switch in efiective thermal communication with thewater therein.

A further object is to provide a fitting having an ex- United States Patent O ternally threaded portion to serve as an exterior mount for athermally responsive switch and an internally threaded end portion forsuspended mounting of a magnesium rod in effective heat conductingcommunication between the water in the tank and the thermally responsiveelectric switch.

Still a further object is to provide a unitary fitting having a seriesof multiple threads to serve as a dual mount for a thremally responsiveelectric switch and a magnesium rod in immersed water relation to a hotwater generating tank whereby the temperature of the contents is incommunicating conductance with both the rod and switch.

Other objects and advantages will appear from a description of anillustrated embodiment of the present invention.

In the drawing:

Figure 1 is a front view in elevation of a hot water generating tank ofthe instantaneous type provided with a tank mount for an electricthermally responsive switch and a magnesium rod suspending portionembodying features of the present inventon, parts thereof being brokenaway and shown in section to clarify the showing.

Figure 2 is a sectional view in elevation of the dual fitting and mounttaken substantially along line II-II of Figure 1.

Figure 3 is a plan view of the switch and mount viewed substantiallyfrom line III-III of Figure 2.

Figure 4 is a schematic wiring diagram showing the electricalrelationship between the various elements for controlling thetemperature of the water in the tank.

The structure selected for illustration is not intended to serve as alimitation upon the scope or teachings of the invention, but is merelyillustrative thereof. There .may be considerable variations andadaptations of all or part of the teachings depending upon the dictatesof commercial practice. The present embodiment comprises a cylindricalupright tank 10 of galvanized steel construction or of the glass-linedvariety which is disposed within a correspondingly shaped and somewhatenlarged jacket or casing 11 having insulation 12 packed therebetween inthe chamber defined by the vertical walls and tops of the respectivetank and jacket 10-11. The

Y tank body 10 has a convex integral top 13 and a concave bottom 14.

The tank 10 has its slightly concave bottom 14 disposed immediatelyabove a standard burner such as a gas burner 15 which communicates witha gas supply pipe 16 provided with an adjustable air regulating shutterof the conventional type (not shown). A closure 17 is provided in thetank jacket or casing 11 immediately below the burner 15 for accessthereto and to a pilot light (not shown) for hand lighting with a match.A transparent sight 18 may be provided in the tank casing 11 to enableviewing the flame produced by the burner 15 while in operation to enableadjustment by regulating the air intake shutters (not shown) to theburner 15.

A cold water inlet pipe 19 threadedly connects with the top and extendsdownwardly for a considerable distance as at 20 for communication withthe bottom interior region of the hot water generating tank 10. A hotwater discharge pipe 22 connects with the top of the tank 10 as at 23for supplying the hot water to the pipe line. A fusible plug 23 withinthe relief valve 24 connects with the top of the tank 10 as at 25, andnormally precludes the flow of water through an overflow pipe 26-27connected thereto for discharge to a sewer or other drainage point. Theheated water 28 within the tank 10 communicates with the fusible plug 23which will melt and open the passage to the overflow pipe 26--27 in the3 a, teventgthewater lzssshonld rise to a dangeroustemperttiture.

30 provided centrally within the top 13 of the tank 10, areceives .an vexternally threaded mounting vfitting D31, 1 in this tinstance havingrareduced exteriorlytthreaded shank :31. terminating in an enlargedhexagonal-flat,surfacehead 1 32: providing for the application ofa'wrenchforrtightent ing engagement with the :tank aperture 29' by meansof the threaded shank 31. The externally threaded shank .31ris,providedwith an axial bore SS-which is interiorly threaded to receivethe'upperthreaded extremity 34 of -an elongatedrrnagnesium rod-35 thatextends downwardly orinwardly belowthetanktop 12 for immersiontinto-thewater 28 forthegreater partof the tank 10.

g To this end; the magnesium rod.35 has.its. externally threaded upperextremity 34 complemental to theinternal .boresthreadt33,of-the-tshankfil to enable the threaded engagement of ,thenmagnesiumrod 35 therewith for. in-' ternal suspension for most of the water depth.within. the tank 10. It will be apparent, therefore that the elongatedmagnesium-rod35 will conduct the most elevated temperature oftheuppenstrataof'thewater 28 to the .body .of the fitting32, and .theenlarged surface thereof insidethe tank housing or jacket 12 andunderneath the ...top insulationlZ will afford the efiective support ofa ..thermostatic bellows typeswitch body 36, in this. instance ofcircular shallow configuration.

The switch body 36 .is attached to the uppersurface -of the magnesiumrodfitting 32by means. of suitable fasteners 37 which extend through casingearsl38. A ,convexlyleshaped thermallytresponsive bottorn.39comprisingpart of the switcheasing, touches theffitting3'2 ,andbecomesdistorted upwardly when the water temperal' .ture reachesuamaximum of 205 degrees'Fahrenheit.which is the safety-limitttherefor. Insotdoing, its insulator vinterior lining 40; touches themetal terminalbridging .element'41. toelevate it into contact with the normallyclosed--terrninals-4243 connected in series with the vlead wires 4445(Figure 4) which are in circuit with a thermocouple 46 and asolenoidtoperated thermostatic valve,mechanism-47. The switch 41opensthe circuit at '205 Fahrenheit to shut off the gas by de-energizinga .solenoid actuated thermostatically responsive valve in a manner wellknown inthe art.

, While I have illustrated and described a preferred embodiment ofthis-invention, it must beunderstood that .the invention is.capable ofconsiderable variation and modification vwithout departing from thespirit of 'the invention. '1, therefore, do not wish to be limited tothe ,.precise details .of constructionset forth, buttdesire to A centralthreaded aperture 29 in an upraised boss availmyself or such variationsand modifications-weenie within the scope ot'the appended claims.

I claim: 1. -An integral unit fitting for an instantaneous hot waterheater tank, comprising a plug member for detachable association withthe top end wall of said tank for communication w-ith-the-sinteriorthereof, said plug member having a fiat surface exterior for mounting ofa heat responsive electrical' switch thereon in conductive relationtherewith, a reduced threaded ,shank:i.depending from said flat surfaceplug member for engagement with a" complemental opening in the 1 topuendwall ofithe' hot water :heater tank, :there :being a bore .in saidthreaded shankrnemberclosedbysaid plug memberandopen at its bottomen'dforcommunication with the tank interior when inassemblediengagementtherewith, an elongated magnesium rod in anchoredattachment at one end thereof with the bore in said threaded shankmember of the plug member. for v suspended, support thereof Within the,hotwatertheater tank'for ,substantiallytthe internal length ,thereof,and-athermally responsive xelectrical switch tmountedionvthetopflatsurface ofsaidzplug member, saidiswitchsadaptedto be connectedelectrically in circuit iwith-anautomaticfuel shut-off valve controllingthe fuel 25.supply to the burnerof the tank, said switch being in directheatconductive connection with said magnesium rod 5 for effectivelyrendering said thermally responsive ..switchtin anopeniorclosed positiondepending uponzthe -ternperature ofnthe rod, whereby-an efiectiveelectrical safety shut-off is -provided :asta part .of an integral unit,fitting. V

2. The combination set forth in claim .1.wherein:1theelectrically."responsive zshut-otf switch, is of the. flat; heat.responsive ..bellows type for .mechanically closing or maintainingtheswitch open depending upon .the tempera- ,ture ofsaid magnesium-rod.i v

. .3. The, combination set forth .invclaim 2 wherein the thermally:responsive electrical switch, flat surface ,-plug ..member, andmagnesiumrod-are fixedly and permanently -.attacheduintlongitudinal axialalignment relat-ive tothe ..latter .for assembly, as a unit with saidtank.

RefereucesCited inthe' file of thispatent UNITED STATES PATENTS

